In an ad hoc network, node apparatuses autonomously form a network. As a result of the node apparatuses autonomously performing communication, the user does not have to set a communication route at any time and there is no necessity for dedicated communication terminals and infrastructures, such as a server and a router, which manage the communication. As related technology, a technique of autonomously forming an ad hoc network by using a HELLO frame has been proposed (see, for example, International Publication Pamphlet No. WO 2011/013165).
When the node apparatuses perform communication, the security of a frame to be communicated has to be secured. Therefore, when the node apparatuses perform communication, after encrypting data to be communicated, the node apparatus transmits a frame to another node apparatus at the other end. As related technology, a technique of performing encryption by obtaining a peak position time by shaking two communication terminal devices several times while holding the communication terminal devices integrally has been proposed (see, for example, Japanese Laid-open Patent Publication No. 2011-130224).